Current technology proposed three kinds of reactor for DME synthesis: the fixed bed (U.S. Pat. Nos. 5,254,596; 4,417,000; 5,908,963; 6,191,175; Xiao et al., 2002; Lu et al., 2002), the slurry reactor (U.S. Pat. No. 5,218,003; US Patent Application Publication No. 2005/0038129 A 1; Brown et al., 1991; Guo, et al., 1997; Wang, et al., 2001; Liu, et al., 2002; Takashi, et al., 2003) and the fluid bed reactor (Xiao, et al., 2002; Lu, et al., 2004). The process for making DME from a hydrogen and carbon monoxide syngas mixture is highly exothermic. The fixed bed reactor can only provide a limited heat removal capability, thus only a low conversion of the syngas can be achieved. At the conditions of P=4 MPa (565 psig), H2/CO molar ratio of 1.0, and gas space velocity of 15,000 ml/gcat/hr to keep the reactor temperature below 270° C. (518° F.), a fixed bed only yields 10.7% CO conversion and 91.9% DME selectivity (Lu, et al., 2002). On the contrary, the slurry reactor can provide an effective temperature control, but the two mass transfer resistances through the gas-liquid and the liquid-solid interfaces limit the DME productivity. In a slurry reactor under the conditions of T=260° C. (500° F.), P=4 MPa (565 psig), H2/CO molar ratio of 1.0, and gas space velocity of 3,000 ml/gcat/hr, the CO conversion and DME selectivity are 17.0% and 70.0% (Wang, et al., 2001).
In a fluid bed reactor, the gas-solid mass transfer resistance is so small that it can be neglected. Excellent temperature control is also achievable due to the vigorous mixing of catalyst particles in the fluid bed. Compared to a fixed bed or a slurry bed under the same conditions of the slurry bed, the CO conversion and DME selectivity in a fluid bed are 48.5% and 97.0% (Lu, et al., 2004). Therefore, the fluid bed reactor is the most promising for production of DME from syngas.
In this invention an improved embodiment to the fluid bed reactor called “fluid pluralized bed reactor” is described in the following sections, figures and examples to further promote effective removal of reaction heat in the reactor in order to minimize the recycle flow rate within the DME synthesis loop.